Resource efficient remediation - WRAP

1 Site at ChinnorSite at FennyStandard practiceMaterial requiring remediation9,720t31,500tVehicle movements5251,700 Cost of disposal 345,600 1,400,000 Best practice (actual)Material requiring remediation11,000t21,600tCost of site remediation 206,000 500,000 Soils transported off 0t100tsite/landfilledCost of additional 50,000 50,000site investigationAvoided cost premium 89,600 850,000for remediationAchieving savings through remediation and onsite reuse of contaminatedmaterial Bellway, Taylor Wimpey and HydrockResource efficient remediationCase studyOverviewThe remediation of sites with contaminatedsoils can be a costly and complex of Escalating Landfill Tax and thepressure to demonstrate sustainability meansclients and developers are now settingrequirements for more efficient remediationsolutions and asking their designers todevelop strategies that avoid the traditional dig and dump solution.

2 This can be the firststep in cutting the costs of waste on a case study looks at two projects thatadopted a best practice approach to MaterialsManagement Planning, in accordance withCL:AIRE s recently published Definition ofWaste: Development Industry Code ofPractice . In each case, the developerbenefited from substantial reductions in cost,shortened programmes and reduced impacton the local case study looks at: Chinnor Cement Works 77ha, requiring ademolition, reclamation and remediationstrategy; and the former BPC & Wheelspan site at Fenny a remediation scheme in a tighturban work illustrates how CL:AIRE s Code ofPractice can help to deliver practical :AIRE (Contaminated Land:Applications in Real Environments) is anorganisation established to stimulate theregeneration of contaminated land byraising awareness of, and confidence in,practical and sustainable remediationtechnologies.

3 The Code of Practiceprovides a structured approach to the reuse of soils on site, and provides a clearprocess for the project team indetermining whether excavated materialsare a waste. It is applicable in Englandand Wales. Costs and savings achieved by housing developers on two remediation sites through adopting an efficient remediation strategyHalving Waste to Landfill Case study: Resource - efficient remediationChinnor Cement WorksThe site at Chinnor is a 77ha former cementworks, cement kiln dust landfill and series ofchalk quarries, with a proportion of the site(7ha) identified as an area for residentialdevelopment.

4 The site is located above amajor chalk aquifer and spring system, withprevious site investigations indicating thatpetroleum hydrocarbons (primarily fromleaking fuel tanks) were present within boththe soils and the groundwater. The challengeChinnor is located on the edge of a villagewith poor access and resultant concerns fromthe public over the impact of demolition, remediation and development of the of the level of contaminants (whichincluded petroleum hydrocarbon andpolycyclic aromatic hydrocarbons) and theneed to protect the local aquifer Resource , theoriginal remedial strategy suggested that9,720t (~5,400m3)1of soils would requiredisposal off-site rather than on siteremediation.

5 This solution was rejected as itwould have required~525 vehicle movements,would be expensive, and impact heavily onthe local community. The challenge was tofind a solution that allowed materials toremain on site in a way that enabledsubsequent re-development (residential andcommercial) and at the same time mitigatedthe risk to the local chalk approachThe client (Taylor Wimpey) instructedHydrock to carry out an appraisal of theprevious site investigations/risk assessment,remedial strategy and costs. Early on,Hydrock identified gaps in the previous riskassessment and noted that the remedialstrategy (dig and dump) was bothunsustainable and costly.

6 Taylor Wimpeywas aware of the potential to save moneythrough alternative solutions and instructedthe design team to explore these. The site investigation works were carried outfollowed by a detailed hydrogeologicalassessment, groundwater risk assessment,human health risk assessment and remedialstrategy in order to develop and refine theConceptual Site Model. The Model is asimplified representation of the siteconditions including geology, hydrogeologyand any significant pollution consideration was given to the finaldevelopment plan and the cut & fillrequirements, which helped the formulationof a viable remediation strategy and robustMaterial Management Plan.

7 (This Plan isintegral to the Code of Practice and can formpart of the Site Waste Management Plan.)On site remediation techniques (using bothbioremediation and soilstabilisation/solidification) were proposed forthe impacted soils, as opposed to anexcavation and disposal option. Uponfurther characterisation and testing, only6,300t (~3,500m3) of materials requiredtreatment, with the remainder suitable forreuse without treatment. 1 Based on 1m3= assessmentMaterial requiring 9,720tremediation off siteVehicle movements525 Cost of disposal 345,600 Final designMaterial requiring 11,000tremediation or reuse on siteCost of site remediation 206,000 Soils transported off 0tsite/landfilledCost of additional 50,000site investigationSummaryCost premium (avoided) for 89,600dig and dump solutionCost premium (avoided)

8 97,777through import of new materialOnce the revised strategy was agreed withthe regulators, Hydrock developed a MaterialManagement Plan that took into account thevolume of material produced by the followingactivities and identified areas within the sitewhere these soil volumes could be suitably re used: demolition arisings; remediation volumes; cut & fill requirements; and soil use in the final development addition, all metal from the demolition ofabove-ground structures was study: Resource - efficient remediationThis Table shows the scale of the savings that wereachieved, resulting both from the avoidance of landfill,and the avoidance of imported BPC & Wheelspan Site (Fenny)This small site ( ) is located in a sensitiveresidential area in Milton Keynes.

9 The sitewas to be developed for residential use, withgardens and areas of public open space. It isbounded on one side by a canal and on theother side by a river (the main receptor), andin its history has had numerous former usesincluding: former town gasworks; paint pigment factory; and a transport client, Bellway NHC, was aware of thecost premium of a traditional (dig and dump)remedial strategy. Hydrock was instructed tocarry out further site investigation and designa scheme that avoided a dig and dumpsolution and as such the associated challengePrevious site investigations indicated site-wide gross contamination including: gasworks waste: - petroleum hydrocarbons; - running tars; - polycyclic aromatic hydrocarbons; - heavy metals; - cyanides.

10 And cadmium impacted soils from paint to the proximity of the river and the highlevel of contamination, the EnvironmentAgency s original preferred strategy was toremove all grossly contaminated soils andinstall an impermeable barrier to preventsubsequent contamination of the river. Thefeasibility study identified that this solutionwould have required the excavation anddisposal of between 27,000t 36,000t(15,000m3to 20,000m3) of largely hazardousmaterials to a landfill 70-80 miles away. Thiswas considered neither economically viablenor sustainable.